$4x^2+4y^2-16=0$

$3abc-9abc^2$

$\left(9-7f\right)\left(81-63f+49f^2\right)$

$\lim_{x\to\infty}\left(\frac{4\left(1-\cos\left(x\right)-2x^2\right)}{x^2\left(1-\cos\left(x\right)\right)}\right)$

$3x^3-3$

$s\:-\:22\:=\:50$

$-\frac{2csc\left(2t\right)}{csc\left(t\right)}$